diff --git a/swh/journal/serializers.py b/swh/journal/serializers.py
--- a/swh/journal/serializers.py
+++ b/swh/journal/serializers.py
@@ -111,3 +111,16 @@
         strict_map_key=False,
         timestamp=3,  # convert Timestamp in datetime objects (tz UTC)
     )
+
+
+def kafka_stream_to_value(stream) -> msgpack.Unpacker:
+    """Return a deserializer for data stored in kafka"""
+    return msgpack.Unpacker(
+        stream,
+        raw=False,
+        object_hook=decode_types_bw,
+        ext_hook=msgpack_ext_hook,
+        strict_map_key=False,
+        use_list=False,
+        timestamp=3,  # convert Timestamp in datetime objects (tz UTC)
+    )
diff --git a/swh/journal/tests/test_stream.py b/swh/journal/tests/test_stream.py
--- a/swh/journal/tests/test_stream.py
+++ b/swh/journal/tests/test_stream.py
@@ -5,24 +5,13 @@
 
 import io
 
-import msgpack
-
-from swh.journal.serializers import msgpack_ext_hook
+from swh.journal.serializers import kafka_stream_to_value
 from swh.journal.writer import get_journal_writer, model_object_dict_sanitizer
 from swh.model.tests.swh_model_data import TEST_OBJECTS
 
 
-def test_write_additions_with_test_objects():
-    outs = io.BytesIO()
-
-    writer = get_journal_writer(
-        cls="stream",
-        value_sanitizer=model_object_dict_sanitizer,
-        output_stream=outs,
-    )
+def fill_writer(writer):
     expected = []
-
-    n = 0
     for object_type, objects in TEST_OBJECTS.items():
         writer.write_additions(object_type, objects)
 
@@ -32,18 +21,57 @@
                 objd.pop("data")
 
             expected.append((object_type, objd))
-        n += len(objects)
+    writer.flush()
+    return expected
+
+
+def test_stream_journal_writer_stream():
+    outs = io.BytesIO()
+
+    writer = get_journal_writer(
+        cls="stream",
+        value_sanitizer=model_object_dict_sanitizer,
+        output_stream=outs,
+    )
+    expected = fill_writer(writer)
 
     outs.seek(0, 0)
-    unpacker = msgpack.Unpacker(
-        outs,
-        raw=False,
-        ext_hook=msgpack_ext_hook,
-        strict_map_key=False,
-        use_list=False,
-        timestamp=3,  # convert Timestamp in datetime objects (tz UTC)
+    unpacker = kafka_stream_to_value(outs)
+    for i, (objtype, objd) in enumerate(unpacker, start=1):
+        assert (objtype, objd) in expected
+    assert len(expected) == i
+
+
+def test_stream_journal_writer_filename(tmp_path):
+    out_fname = str(tmp_path / "journal.msgpack")
+
+    writer = get_journal_writer(
+        cls="stream",
+        value_sanitizer=model_object_dict_sanitizer,
+        output_stream=out_fname,
     )
+    expected = fill_writer(writer)
+
+    with open(out_fname, "rb") as outs:
+        unpacker = kafka_stream_to_value(outs)
+        for i, (objtype, objd) in enumerate(unpacker, start=1):
+            assert (objtype, objd) in expected
+        assert len(expected) == i
+
+
+def test_stream_journal_writer_stdout(capfdbinary):
+    writer = get_journal_writer(
+        cls="stream",
+        value_sanitizer=model_object_dict_sanitizer,
+        output_stream="-",
+    )
+    expected = fill_writer(writer)
+
+    captured = capfdbinary.readouterr()
+    assert captured.err == b""
+    outs = io.BytesIO(captured.out)
 
+    unpacker = kafka_stream_to_value(outs)
     for i, (objtype, objd) in enumerate(unpacker, start=1):
         assert (objtype, objd) in expected
     assert len(expected) == i
diff --git a/swh/journal/writer/__init__.py b/swh/journal/writer/__init__.py
--- a/swh/journal/writer/__init__.py
+++ b/swh/journal/writer/__init__.py
@@ -3,7 +3,9 @@
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
-from typing import Any, Dict, Optional, TypeVar
+import os
+import sys
+from typing import Any, BinaryIO, Dict, Optional, TypeVar
 import warnings
 
 from typing_extensions import Protocol
@@ -56,6 +58,14 @@
         from .stream import StreamJournalWriter as JournalWriter
 
         assert "output_stream" in kwargs
+        outstream: BinaryIO
+        if kwargs["output_stream"] == "-":
+            outstream = os.fdopen(sys.stdout.fileno(), "wb", closefd=False)
+        elif isinstance(kwargs["output_stream"], (str, bytes)):
+            outstream = open(kwargs["output_stream"], "wb")
+        else:
+            outstream = kwargs["output_stream"]
+        kwargs["output_stream"] = outstream
     else:
         raise ValueError("Unknown journal writer class `%s`" % cls)
 
diff --git a/swh/journal/writer/stream.py b/swh/journal/writer/stream.py
--- a/swh/journal/writer/stream.py
+++ b/swh/journal/writer/stream.py
@@ -45,3 +45,6 @@
     ) -> None:
         for object_ in objects:
             self.write_addition(object_type, object_, privileged)
+
+    def flush(self):
+        self.output.flush()